Adhesive drive for a tape-shaped signal carrier



Oct. 8, 1963 M. FISCHER 3,106,319

ADHESIVE DRIVE FOR A TAPE-SHAPED SIGNAL CARRIER Filed July 24, 1959achve lager n 1 slgnalcarr|er garner drlvlng cghnder l. f skinless siddiamond compound cglinder pressing roller INVENTOR Markus FlscherATTORNEY United States Patent 3,106,319 ADHESIVE DRIVE FOR A TAPE-SHAPEDSIGNAL CARRIER Markus Fischer, Garbeuweg 13, Bumpliz, near Bern,Switzerland Filed July 24, 1959, Ser. No. 829,206 Claims priority,application Switzerland July 29, 1958 6 Claims. (Cl. 226-193) Thisinvention relates to an adhesion drive for a tapesh-aped signal carrieradapted to be fed through a signal recording or signal reproducingapparatus, such as a mag netic sound tape, a perforated tape or thelike, wherein the speed of the signal carrier is controlled by contactthereof with a rotating cylinder.

The most important problem with adhesion drives of this kind, which hasnot been solved satisfactorily up to date, is the slip between thesignal carrying tape and the said rotating cylinder which must beavoided to prevent fluctuations of the tape speed. It is well known thatfluctuations of the speed of a magnetic sound recorder result indistortions of the high frequencies or in fluctuations of the soundreproduced from the tape, according to whether such speed fluctuationsare of high or low frequency. Further when using sound recording tapesfor recording the accompanying sound of films or television, thesynchronism between the picture and the sound is gradually lost duringreproduction due to the continuously occurring slip between the soundrecording tape and its driving cylinder.

Attempts have been made for overcoming these difficulties by coating thedriving cylinder with rubber, plastic material or the like forincreasing the adhesion, but this measure has the drawback that thedriving cylinder must be cleaned rather frequently and that the softsurface is subject to deformation after a relatively short time ofoperation. For avoiding :these defects the use of a hardened androughened steel cylinder was also proposed, whereby the tape is pressedagainst the cylinder by means of a roller of soft material such as nylonTo allow the use of a relatively thin steel, driving cylinder the activelayer of the sound recording tape was fed through the machine in contactwith the driving cylinder and the nylon roller applied with a very highpressure. However, it was found that the roughness of the hardened steelcylinder is rapidly ground off by the sound recording tape so that theadhesion between the cylinder and the tape decreases to values allowingundue slip between these elements. Therefore, extremely thick drivingcylinders have been used for first class instruments. However, even thismeasure does not entirely avoid slip between the driving cylinder andthe sound recording tape.

It is the main object of this invention to provide an adhesion drivewhich is simple in manufacture and by which slippage between the drivingcylinder and the tape is completely avoided, said drive comprising adriving roller having a cylindrical surface to be contacted by the saidtape-shaped signal carrier, or tape, the said surface being providedwith hard projecting particles such as diamond particles.

The novel features that are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of a specificembodiment when read in connection with the accompanying drawings, andin which:

FIG. 1 is a fragmentary, enlarged sectional view showing a portion ofthe driving cylinder engaged by a tape;

FIG. 2 is a similar view illustrating the manufacturing process utilizedto embed the diamond particles in the driving cylinder; and

FIG. 3 is a plan view illustrating a pressing roller urging the tapeinto contact with the rotating driving cylinder. Q

Referring now to the drawings, the driving cylinder, or roller, shouldbe made of a relatively soft, stainless material such as unhardenedstainless steel, coppenbrass or a plastic material,- diamond particleshaving a size in the order of 20 to p. for a cylinder diameter of 5 to10 mm. being rolled into the surface of the driving cylin der in such amanner that approximately half the particles project from the surface ofthe cylinder. The sizeof the particles may increase with increasingdiameter of the driving cylinder, and the size should be chosen in sucha way that fluctuation of the driving speed is impossible due toinequalities in the engagement of the tape with the particles. Further,in order to obtain proper engagement of the tape with the projectingportions of the urging the tape against the driving cylinder may bedecreased to a fifth or tenth of the pressure used in known apparatuses.A pressing roller should be used having an axial length not exceedingthe width of the tape as shown in FIG. 3 in order that the rollercontacts the tape only and not the driving roller. It was found that aroller contacting the tape and the driving cylinder often causesdeviations of the tape speed from the circumferential Speed of thedriving cylinder because the tape is driven by the pressing roller. Itis a particular advantage of this invention that the driving cylinder ispractically not worn due to the absence of slip and due to the highhardness of the particles forming the driving surface. When using asynchronous motor for rotating the driving cylinder, an exactlysynchronous running of the tape may be secured for considerable runningperiods of the apparatus. Due to the reduced radial pressure of thepressure roller, friction in the driving system may substantially bereduced so that smaller flywheels and smaller driving rnotors may beused, and the total dimensions, weight and cost of the apparatus mayaccordingly be reduced. If sufiicient poll is set up in the tape andwhen the looping angle or angle of grip of the tape on the drivingcylinder is relatively great, a pressing roller may be dispensed with.In this manner, an apparatus Without any part of plastic or other softmaterial may be obtained. It is further possible to increase theadhesion between the driving cylinder and a sound recording tape of asound recorder without solenoid-operated pressure roller for fast start,by passing the active layer of the tape in contact with the drivingcylinder, whereby the size of the hard particles of the driving cylinderrnay preferably be equal to the size of the particles of the active tapelayer. In this way some sort of gear-like engagement between theparticles of the tape and of the cylinder will occur resulting in anabsolutely slip-less drive.

Manufacture of the driving cylinder is relatively simple. However, someimportant indications mentioned here after should be followed. Thesurface of the cylinder is to be worked, for instance ground, to be verysmooth.

To the so smoothened surface a pasty substance contain- I a slowlyapproached to a distance in the order of of a millimeter from thecylinder surface, whereby the pasty substance is first equallydistributed on the cylinder surface without pressing the hard particlesinto the cylinder surface. When the desired distribution and thicknessof the substance has been attained the roller is further approachedsubstantially into contact with the surface of the driving cylinderwhereby the particles are rolled into the relatively soft cylindersurface. As an example, the hardened outer race of a ball bearing may beused as a pressure roller, this ball bearing being tixcd on a slightlyresilient support. During this operation the speed of the cylindersurface should be relatively low and should not exceed 10 cm./sec.Smoothing the cylinder surface and providing it with the hard particlesin the manner just described should be done before the cylinder isremoved from its clamping in the lathe, or other machine used forfabricating the driving cylinder in order to first obtain an absolutelycylindrical driving surface in which all hard particles are thereafterinserted to an absolutely equal depth.

This invention may be used in all kinds of apparatus used insound-picture production, in magnetic picture recording machines fortelevision, and for automatic control of machines by means of perforatedtapes or the like, wherein the higher precision and the longer lift-timeof the drive are very important.

Of course the drive may also be used where the cylinder is not driven bya motor and does not drive tie tape, but where the cylinder is driven bythe tape. Such an arrangement is used when equalizing the speed of tapesfed by means of toothed rollers engaging perforations or" the tape, suchtapes being fed over an adhesion cylinder connected to a flywheel, theadhesion cylinder and flywheel equalizing fluctuations of the tape speeddue to the drive thereof by means of toothed rollers.

The long life-time of the rough surface of the driving cylinder is ofparticular advantage for machines used for producing tape copies from anoriginal, such machines having very high running times of up to 24 hoursper day.

What I claim is:

1. An adhesion drive for a magnetic recording tape having an activelayer comprising individual particles of magnetizablc material at oneside of said tape, comprising a rotating cylinder and means formaintaining the said tape in contact with the rotating cylinder in orderto maintain the speed of the tape equal to the circumferential speed ofthe rotating cylinder, the said cylinder having a. smooth cylindricalsurface, hard particles being partially pressed and thus anchored in thesaid surface of the cylinder, the remaining portion of the particlesprojecting from the said surface and contacting the active layer of thesaid magnetic recording tape, the said hard particles having a size inthe same order as the size of the individual particles of the saidactive layer.

2. An adhesion drive for a recording tape, comprising a rotatingcylinder having a smooth cylindrical surface and means for maintainingthe said tape in contact with the cylindrical surface of the rotatingcylinder in order to maintain the speed of the tape equal to thecircumferential speed of the rotating cylinder, hard particles beinganchored in the said cylindrical surface of the rotating cylinder withportions of all particles being inserted into the cylindrical surface toan equal depth, the remaining portion of the particles projecting fromthe cylindrical surface and uniformly contacting the tape on thecylindrical driving surface.

3. An adhesion drive for a recording tape, comprising a rotatingcylinder having a smooth cylindrical surface and means for maintainingthe said tape in contact with the cylindrical surface of the rotatingcylinder in order to maintain the speed of the tape equal to thecircumferential speed of the rotating cylinder, hard particles having asize of less than 1 being anchored in the said smooth cylindricalsurface of the rotating cylinder with portions of such particles beinginserted into the cylindrical surface of the rotating cylinder, theremaining portion of the particles projecting from the cylindricalsurface and contacting the said recording tape, said particles beingsubstantially uniformly distributed at random on said smooth cylindricalsurface.

4. An adhesion drive according to claim 3, comprising particles ofsubstantially equal size.

5. An adhesion drive according to claim 3, comprising a rotatingcylinder of stainless steel.

6. An adhesion drive for recording tape, comprising a metallic rotatingcylinder having a smooth cylindrical surace and means for maintainingthe said tape in contact with the cylindrical surface of the rotatingcylinder in order to maintain the speed of the tape equal to thecircuinferential speed of the rotating cylinder, the said cylindricalsurface having a diameter in the order of 5-10 mm. and hard particleshaving a size in accordance with the said diameter of the cylindricalsunface in the order of 20-100, being anchored in the said cylindricalsurface of the rotating cylinder with portions of such particlesinserted into the cylindrical surface of the rotating cylinder, theremaining portion of the paiticles projecting from the cylindricalsurface and contacting the said recording tape.

References Cited in the file of this patent UNITED STATES PATENTS1,072,564 Bowers Sept. 9, 1913 1,097,565 Straubel May 19, 1914 1,579,657Perrault Apr. 6, 1926 1,800,443 Dustan et al Apr. 14, 1931 2,024,007McColloch et al Dec. 10, 1935 2,367,203 Cooper Ian. 16, 1945 2,490,548Schultz Dec. 6, 1949 2,499,700 Tinkham et al. Mar. 7, 1950 2,555,319Cross June 5, 1951 2,568,000 Gunn Sept. 18, 1951 2,622,873 Wenneche Dec.23, 1952 2,827,389 Garner Mar. 18, 1958 2,920,148 Munroe Jan. 5, 1960FOREIGN PATENTS 317,214 Switzerland Dec. 29, 1956 956,341 France Aug. 1,1949

2. AN ADHESION DRIVE FOR A RECORDING TAPE, COMPRISING A ROTATINGCYLINDER HAVING A SMOOTH CYLINDRICAL SURFACE AND MEANS FOR MAINTAININGTHE SAID TAPE IN CONTACT WITH THE CYLINDRICAL SURFACE OF THE ROTATINGCYLINDER IN ORDER TO MAINTAIN THE SPEED OF THE TAPE EQUAL TO THECIRCUMFER-